WiFi blog

More than 210,000 users have watched a YouTube video of our data center operations team cabling a row of server racks in San Jose. More than 95 percent of the ratings left on the video are positive, and more than 160 comments have been posted in response. To some, those numbers probably seem unbelievable, but to anyone who has ever cabled a data center rack or dealt with a poorly cabled data center rack, the time-lapse video is enthralling, and it seems to have catalyzed a healthy debate: At least a dozen comments on the video question/criticize how we organize and secure the cables on each of our server racks. It's high time we addressed this "zip ties v. hook & loop (Velcro®)" cable bundling controversy.

The most widely recognized standards for network cabling have been published by the Telecommunications Industry Association and Electronics Industries Alliance (TIA/EIA). Unfortunately, those standards don't specify the physical method to secure cables, but it's generally understood that if you tie cables too tight, the cable's geometry will be affected, possibly deforming the copper, modifying the twisted pairs or otherwise physically causing performance degradation. This understanding begs the question of whether zip ties are inherently inferior to hook & loop ties for network cabling applications.

As you might have observed in the "Cabling a Data Center Rack" video, SoftLayer uses nylon zip ties when we bundle and secure the network cables on our data center server racks. The decision to use zip ties rather than hook & loop ties was made during SoftLayer's infancy. Our team had a vision for an automated data center that wouldn't require much server/cable movement after a rack is installed, and zip ties were much stronger and more "permanent" than hook & loop ties. Zip ties allow us to tighten our cable bundles easily so those bundles are more structurally solid (and prettier). In short, zip ties were better for SoftLayer data centers than hook & loop ties.

That conclusion is contrary to the prevailing opinion in the world of networking that zip ties are evil and that hook & loop ties are among only a few acceptable materials for "good" network cabling. We hear audible gasps from some network engineers when they see those little strips of nylon bundling our Ethernet cables. We know exactly what they're thinking: Zip ties negatively impact network performance because they're easily over-tightened, and cables in zip-tied bundles are more difficult to replace. After they pick their jaws up off the floor, we debunk those myths.

The first myth (that zip ties can negatively impact network performance) is entirely valid, but its significance is much greater in theory than it is in practice. While I couldn't track down any scientific experiments that demonstrate the maximum tension a cable tie can exert on a bundle of cables before the traffic through those cables is affected, I have a good amount of empirical evidence to fall back on from SoftLayer data centers. Since 2006, SoftLayer has installed more than 400,000 patch cables in data centers around the world (using zip ties), and we've *never* encountered a fault in a network cable that was the result of a zip tie being over-tightened ... And we're not shy about tightening those ties.

The fact that nylon zip ties are cheaper than most (all?) of the other more "acceptable" options is a fringe benefit. By securing our cable bundles tightly, we keep our server racks clean and uniform:

The second myth (that cables in zip-tied bundles are more difficult to replace) is also somewhat flawed when it comes to SoftLayer's use case. Every rack is pre-wired to deliver five Ethernet cables — two public, two private and one out-of-band management — to each "rack U," which provides enough connections to support a full rack of 1U servers. If larger servers are installed in a rack, we won't need all of the network cables wired to the rack, but if those servers are ever replaced with smaller servers, we don't have to re-run network cabling. Network cables aren't exposed to the tension, pressure or environmental changes of being moved around (even when servers are moved), so external forces don't cause much wear. The most common physical "failures" of network cables are typically associated with RJ45 jack crimp issues, and those RJ45 ends are easily replaced.

Let's say a cable does need to be replaced, though. Servers in SoftLayer data centers have redundant public and private network connections, but in this theoretical example, we'll assume network traffic can only travel over one network connection and a data center technician has to physically replace the cable connecting the server to the network switch. With all of those zip ties around those cable bundles, how long do you think it would take to bring that connection back online? (Hint: That's kind of a trick question.) See for yourself:

The answer in practice is "less than one minute" ... The "trick" in that trick question is that the zip ties around the cable bundles are irrelevant when it comes to physically replacing a network connection. Data center technicians use temporary cables to make a direct server-to-switch connection, and they schedule an appropriate time to perform a permanent replacement (which actually involves removing and replacing zip ties). In the video above, we show a temporary cable being installed in about 45 seconds, and we also demonstrate the process of creating, installing and bundling a permanent network cable replacement. Even with all of those villainous zip ties, everything is done in less than 18 minutes.

Many of the comments on YouTube bemoan the idea of having to replace a single cable in one of these zip-tied bundles, but as you can see, the process isn't very laborious, and it doesn't vary significantly from the amount of time it would take to perform the same maintenance with a Velcro®-secured cable bundle.

There are already 34 million workers who telecommute at least occasionally in the U.S. According to Forrester research, this figure is expected to swell to 63 million by 2016, fueled by worldwide broadband adoption, better collaboration tools, and growing management experience.

We are one of the most experienced and established fiber optic installation companies in the South California metropolitan area. We specialize in the complete installation of business communication systems with structured voice and data cabling design and infrastructure.

Wi-Fi is the fastest growing and most popular technology that allows an electronic device to exchange data wirelessly over a computer network, including high-speed Internet connections. In the early 2000′s, many cities and businesses around the world announced plans to construct and implement Wi-Fi networks.

THIS ISN’T YOUR FATHERS WIFI ANYMORE………

As the commercial population becomes more mobile, two trends have emerged for Wi-Fi solutions to address:

The 802.11ac specification offers a maximum data transfer speed of more than 3Gbps and provides support for up to eight streams. This means one thing: significantly faster data transfer speeds.

The challenge for 802.11ac is to meet today’s functional demands and the explosive wireless market growth that is expected to triple over the next three to five years. In addition networks are adapting to the growing demands of users with HetNet (heterogeneous network). The concept of a HetNet is a network with many different aspects and technologies, from Wi-Fi to femtocells, all working together. This means Wi-Fi technicians are helping you get quicker data rates and making services work better. The term HetNet is also used in wireless networks using different access technologies. For example, a wireless network which provides a service through a wireless LAN and is able to maintain the service when switching to a cellular network is called wireless HetNet.

School Board Chair Patti Bacchus said the service is being installed because the district is out of step with an educational technology that is increasingly conducted online and with students armed with laptops and smartphones.

The initial focus will be on secondary schools but a request for proposals issued last month shows the school district is seeking a contractor to provide service for 100 sites.

Network cabling today is used for many other purposes besides computer networking. Network cabling is also used as control cable in Building Maintenance Systems and Access Control Systems. Understanding Cable Type

Before you can really understand how cable networking works, you need to know about the various cables and how they work. Here is a rundown of the cables that are most commonly used for network cabling:

Unshielded/Shielded Twisted Pair – This is the type of cable that is used for many Ethernet networks. Twisted pair cable is limited to 295′ on a horizontal run. Twisted pair cable is used for many applications. Standard station cabling for computers and VOIP phones, wireless access points, network cameras, access control and building maintenance systems are just a few. Fiber Optic – Fiber optic cable is primarily used as backbone cable although it is being used more and more as station cable (think FIOS). Fiber cables can cover great distances(hundreds of meters) as opposed to copper cable. Fiber cables transmit light as opposed to electrical current. Fiber optic cable is a great choice for high speed reliable communications.

Coaxial Cable – Coaxial cable usually falls under the scope of work of the network cabling installation contractor. Coax will be used for the cable television locations within the space you are cabling. Network Cabling Components

RJ 45 Connector – The RJ-45 connector is installed on the end of a network cable. Contrary to popular belief wireless devices STILL need to be fed with network cabling.

Cable Supports – (Commonly called J-Hooks) Cable supports are mounted in the ceiling as a support structure for your cable bundles. Wire Managers – Wire managers are installed between patch panels and switches to manage patch cables. Firestop Sleeves – Firestop sleeves are a vital part of any network cabling installation these days. Cable Labels – All cables and termination points should have a unique label.

With 802.11n the best practice recognized in the industry is to install the access points (AP) in the room. Installing 802.11n wireless network access points in the hallway introduces a number of issues that can be avoided by just installing them in the room where the wireless clients most likely are found.

The reasons for installing access points in the room and the not the hallways are;

Interference – To avoid co-channel and adjacent channel interference caused by the efficiencies of 802.11n and MIMO. Too much co-channel or adjacent channel interference will degrade the performance of your wireless network. Installing APs in the room uses walls to buffer the signal to reduce these types of interference.

Devices – Low power mobile devices like iPads, Chromebooks, smart phones, tablets, etc… do not have the transmit capabilities that laptops have and as a result need the AP to be closer to them. i.e. – in the room!

Automated RF management – As a side effect of the ability for 802.11n at getting signal everywhere access points will decrease their power levels to avoid inducing additional interference into the environment. This results in shrinking RF coverage and reduced signal at the clients. Putting the AP in the room eliminates this issue completely.

5 Ghz – More and more devices are coming with 5Ghz chipsets for wireless now and will continue in the future because 2.4GHz wireless is so overcrowded. The downside is that 5GHz cannot transmit through building materials as far. This is resolved by installing the AP in the room where the signal does not have to go through building materials or as many as it would in a hallway.

Hallway deployment shows less coverage of rooms. In room deployment would provide better.

*Note - In some situations however an in hallway installation can work. Typically this is achievable in an office environment where coverage is the design goal and rarely would two APs be too close together or a wall would not be dividing them.

On the wall or on the ceiling?

Manufacturers design their APs to be installed in specific locations. Some manufacturers claim their APs can be installed in either location. However, this is generally a compromised solution because no AP or antenna is ideal for all locations.

In our experience it is typically the ceiling location that benefits the end users the most. There are fewer obstructions to deal with when the RF signal is coming from above and it provides the best direct path to the end user devices. With that said we also realize and have encountered areas where the ceiling option was not achievable. For these installations we chose another access point from the same manufacturer with an appropriate antenna type and modified where we install them on the walls. We might choose two adjacent walls to mount the APs so that the wireless end user is able to have a direct signal from one or the other APs in the environment.

Antenna type is important in knowing where the AP will be located and what the intended coverage is.

Above or below the ceiling?

Our recommendation to this question is almost always going to be below the ceiling. This is based on experience and best practice recommendations from the manufacturers that we work with. Here are some reasons why you want to place the AP below ceiling level in your installation;

Obstructions – above the ceiling there are almost always obstructions that impair the functionof the AP. The obstructions found aboveceiling are HVAC ducts, waste and water pipes, electrical conduit, metal lightfixtures, fire doors, and a plethora of objects too numerous to list. All ofthese objects have the same behavior and that is they alter the APs RF signaland impede its’ ability to give you the coverage and performance you require.

Environmental – above the ceiling also introduces the AP into an environment that may not be favorable to its’ required operations. These variables could be an unventilatedenvironment which would cause the AP to run hot which is never good forelectronics. The environment might be extremely dusty which is also not goodfor electronics. There could also be unshielded electrical wiring above ceilingwhich can interfere with the signal as well as data in the AP.

There are a lot of factors to consider when deciding where to install your wireless network access points. Hopefully what we have pointed out here will help you choose the optimal placement to get the best performance out of your shiny new wireless network system or your current one that needs some help.

posted from :http://www.securedgenetworks.com/secure-edge-networks-blog/bid/93441/How-Do-I-Install-My-Wireless-Network-Access-Points

One of our roles in every data center installation is to bridge communication gaps between functional groups so goals can be met to everyone’s satisfaction.

That’s a consultative role, one that takes boots on the ground at first, and an ongoing relationship thereafter. At Raritan, we prefer to be on-site at deployments, working side-by-side with customers.Sometimes, the work we do isn’t particularly technical but rather logistical. Knowing, for example, that a customer is going to have 200 racks installed, we make sure that PDUs show up prior to installation so critical dates aren’t missed.

Often, PDU installation is only a small part of the process that gets us about 30% of the way there. Assuming the customer has the power strips, sensors and software running on Day 1, we can then help immediately start extracting value from their investment by Day 2. Now that they have all this great new power consumption and environmental data, what are they going to do differently? By the third day, we can start the iterative process of making those changes and measuring gains.

You’d be surprised to learn how many data centers are still plagued by server underutilization with one or very few applications running on a single server. It’s exacerbated by the fact that this particular server might be the least efficient machine to actually perform these tasks.

People still have a hard time unplugging stuff. Our system gives them the data to take an intelligent step forward. The conversation between Data Center Manager and User might go something like this: “You’re telling me you use this server?” And the user says “Yes, we use it.” With this new data, the manager can show the user that in the last 90 days the server hasn’t fluctuated at all from a power perspective and the network traffic has been essentially zero. The manager can now tell the user, “What you’re telling me doesn’t match the data we’re seeing. Let’s migrate this to a virtual appliance. We’ll decommission the other one, and if you have a service impact, we can discuss reprovisioning it.”

Hard data gives you a firm basis upon which to realize power and cooling efficiencies. It’s very important to Raritan to make sure our customers achieve the value that they are expecting from our product. The faster we can turn data into actionable information. The better the

posted from :http://blog.raritan.com/2013/09/the-consultative-role-in-data-center-installations/

Computer networks for the home and small business can be built using either wired or wireless technology. Wired Ethernet has been the traditional choice in homes, but Wi-Fiwireless technologies are gaining ground fast. Both wired and wireless can claim advantages over the other; both represent viable options for home and other local area networks (LANs).

Below we compare wired and wireless networking in five key areas:

ease of installation

total cost

reliability

performance

securityAbout Wired LANs

Wired LANs use Ethernet cables and networkadapters. Although two computers can be directly wired to each other using an Ethernet crossover cable, wired LANs generally also require central devices like hubs, switches, or routers to accommodate more computers.

For dial-up connections to the Internet, the computer hosting the modem must run Internet Connection Sharing or similar software to share the connection with all other computers on the LAN.Broadband routers allow easier sharing of cable modem or DSL Internet connections, plus they often include built-in firewall support.

Installation

Ethernet cables must be run from each computer to another computer or to the central device. It can be time-consuming and difficult to run cables under the floor or through walls, especially when computers sit in different rooms. Some newer homes are pre-wired with CAT5 cable, greatly simplifying the cabling process and minimizing unsightly cable runs.

The correct cabling configuration for a wired LAN varies depending on the mix of devices, the type of Internet connection, and whether internal or external modems are used. However, none of these options pose any more difficulty than, for example, wiring a home theater system.

After hardware installation, the remaining steps in configuring either wired or wireless LANs do not differ much. Both rely on standard Internet Protocol and network operating systemconfiguration options. Laptops and other portable devices often enjoy greater mobility in wireless home network installations (at least for as long as their batteries allow).

Cost

Ethernet cables, hubs and switches are very inexpensive. Some connection sharing software packages, like ICS, are free; some cost a nominal fee. Broadband routers cost more, but these are optional components of a wired LAN, and their higher cost is offset by the benefit of easier installation and built-in security features.

Reliability

Ethernet cables, hubs and switches are extremely reliable, mainly because manufacturers have been continually improving Ethernet technology over several decades. Loose cables likely remain the single most common and annoying source of failure in a wired network. When installing a wired LAN or moving any of the components later, be sure to carefully check the cable connections.

Broadband routers have also suffered from some reliability problems in the past. Unlike other Ethernet gear, these products are relatively new, multi-function devices. Broadband routers have matured over the past several years and their reliability has improved greatly.

Performance

Wired LANs offer superior performance. Traditional Ethernet connections offer only 10 Mbpsbandwidth, but 100 Mbps Fast Ethernet technology costs little more and is readily available. Although 100 Mbps represents a theoretical maximum performance never really achieved in practice, Fast Ethernet should be sufficient for home file sharing, gaming, and high-speed Internet access for many years into the future.

Wired LANs utilizing hubs can suffer performance slowdown if computers heavily utilize the network simultaneously. Use Ethernet switches instead of hubs to avoid this problem; a switch costs little more than a hub.

Security

For any wired LAN connected to the Internet, firewalls are the primary security consideration. Wired Ethernet hubs and switches do not support firewalls. However, firewall software products like ZoneAlarm can be installed on the computers themselves. Broadband routers offer equivalent firewall capability built into the device, configurable through its own software.posted from:http://compnetworking.about.com/cs/homenetworking/a/homewiredless.htm